CO-OFDM (COherent light-Orthogonal Frequency Division Multiplexing) system channel estimation method based on channel impulse response filtering

Abstract

The invention provides a CO-OFDM (COherent light-Orthogonal Frequency Division Multiplexing) system channel estimation method based on channel impulse response filtering, which can improve the noise resistance capability for channel estimation with smaller system expenditure. The method comprises the following steps of: carrying out IFFT (Inverse Fast Fourier Transform) transform on a channel transfer function estimated by an LS (Least Square) channel to obtain a channel impulse response; calculating the length of the channel impulse response according to optical fiber channel parameters, such as dispersion, polarization mode dispersion and the like; constructing a Blackman window function according to the length of the channel impulse response; carrying out time domain multiplication on the channel impulse response and the Blackman window function; carrying out FFT transform on the processed channel impulse response to obtain a channel transfer function of which the noise is filtered out; and applying the updated channel transfer function to subsequent channel balancing.

Description

technical field [0001] The invention relates to a channel estimation method of a coherent optical orthogonal frequency division multiplexing (CO-OFDM) system, more specifically, relates to a channel estimation method based on channel impulse response filtering. Background technique [0002] Orthogonal Frequency Division Multiplexing (OFDM), as an advanced technology in the physical layer of wireless communication systems, has been widely used in 802.11a / g WiFi, HiperLAN2, 802.16WiMAX and other wireless network standards as well as digital audio and video in many countries Broadcasting (DAB, DVB-T) technology. OFDM technology has also been widely studied in optical fiber communication systems, and it is used as a solution to realize high-speed long-distance transmission. Among the many solutions of the optical OFDM system, the coherent optical OFDM (CO-OFDM) system is the most superior. The CO-OFDM system combines the advantages of coherent detection technology and OFDM mod...

AI Technical Summary

Problems solved by technology

The TDA algorithm needs to use multiple consecutive training symbols, which will greatly increase the system overhead and affect the transmission efficiency

Although the ISFA algorithm reduces the overhead, it also reduces the tolerance of the system to the cumulative dispersion and polarization mode dispersion. When the dispersion or polarization mode dispersion is large, it will introduce interference between subcarriers.

Although dispersion compensation can be performed on the received signal before channel estimation to improve the ISFA algorithm's tolerance to dispersion and polarization mode dispersion, this undoubtedly increases the complexity of the algorithm and the difficulty of implementation

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